Streamflow droughts assessment in Kurdistan Province, Iran

In this paper, we analyzed the streamflow droughts based on the Percent of Normal Index (PNI) and clustering approaches in the Kurdistan Province, Iran, over the 1981-2010. The Kolmogorov-Smirnov (K-S) test was considered for streamflow time series and the results of K-S test indicated that streamflow time series did follow the normal distribution at the 0.05 significance level. Generally, the results showed that mostly streamflow droughts have been commenced since 1997 and also in most of the stations the extreme streamflow droughts occurred in 1997-2001. Furthermore, the number of drought events in each station showed that the extreme streamflow drought status in the Shilan station was the highest number with value 12, while the Tunnel Chehelgazi showed the lowest extreme drought status with value 4. Meanwhile, we used clustering approaches in order to explore homogeneities area which suffered from streamflow droughts. We selected two different clusters. So that,  5 stations out of 6 stations were classified in cluster 1 having the same situation in most  years. The Shilan station had the specific conditions compared with other stations and classified in cluster 2. As a result, the clustering analysis was able to explore homogenous areas suffered from the same streamflow droughts. Therefore, the results of this work showed that the study area suffered from streamflow drought events over the three last decades, especially in last 14 years which can lead to many impacts on environment and ecosystems.